Vacuum deaerators are known mechanisms for the separation of liquids and gases. Specifically, vacuum deaerators separate entrained gases contained in the liquids, in part by extending the surface area of the liquid. Entrained gases, for example, air bubbles, may become entrained in liquids for numerous reasons. For instance, applications that require mixing a finely divided solid in a liquid may generate air bubbles. The gases, which are adsorbed to the surface of the solids or contained in the interstitial spaces of the solids, are released into the liquid, thus resulting in entrained gases in the liquid. The stability of the air bubbles in the liquid depends on product viscosity and surface tension.
Deaeration of liquid compositions is desirable for various reasons. First, deaeration may improve the aesthetic look and feel of a product. Entrained air can make a liquid unsightly due to pockmarks or foam; thus, many value-added food, pharmaceutical, and cosmetic products are deaerated for appearance sake alone. Second, deaeration may also ensure product usability. Chemical products such as epoxies, caulking compounds, and adhesives often need to be deaerated for effective ease of application and even coating. Third, deaeration ensures proper volumetric filling of containers. Volumetric filling of liquids is unreliable if the density of the product is inconsistent. During filling, entrained air may cause liquid splattering due to escaping air “burping” as the liquid is expelled from the filling nozzle into the container. Fourth, deaeration aids transport of chemicals. Many bulk chemicals cannot be easily pumped because of compression or cavitation due to entrained air. This problem plagues many pumps, e.g., centrifugal and positive displacement pumps, thus removal of entrained gases is desirable. Fifth, deaeration may facilitate improved product storage. For instance, deaerated or foaming products may cause various problems in bulk storage by yielding false readings to various types of level indicators. Sixth, deaeration improves product stability and shelf life. Many liquid products oxidize or degrade due to the presence of oxygen or carbon dioxide. As a result, removing entrained air can increase the stability of many food and chemical products.
Referring to FIGS. 1 and 3, the Fryma/Koruma® (“Koruma”) continuous vacuum deaerator 100, a known deaerator distributed by Fryma/Koruma®, is shown schematically. The Koruma deaerator 100 comprises a conical shaped vessel 102 with a cover 103 and side walls 104. The Koruma deaerator 100 comprises a liquid feed port 110 mounted into the cover 103, and extending downward into the distributor plate 130, and further comprises a drive shaft 180. As shown in FIGS. 1 and 3, the distributor plate 130 comprises screens 132, typically three screens, having 1 mm to 3 mm holes. The plate 130 further comprises a seal 140 disposed in the liquid flowpath and configured to ensure that liquid is dispersed only through the screens 132. The Koruma deaerator 100 atomizes the liquid into thousands of droplets by forcing the liquid through the screen 132 holes of the distributor plate 130, thereby extending the surface area and removing air bubbles from the liquid. The entrained gases, or air bubbles, are removed from the vessel by a vacuum 120 having a conduit mounted in the cover 103, and comprising a vacuum pump 124 and a vacuum line 122. The deaerated liquid is delivered out of the vessel 102 via the product discharge tube 160. Although capable of removing air bubbles, the Koruma deaerator 100 imparts shear to the liquid as the product is forced through the screens 132.
Referring to FIG. 2, components of the Cornell Versator® 200, a known deaerator distributed by the Cornell Machine Company, are shown schematically. The Versator 200 comprises an elliptical disc distributor plate 220, and a feed port 210 providing a liquid feed near the center of the distributor plate 220. Rotated by the drive shaft 280, the distributor plate 220 exerts a centrifugal force on the entrained liquid thus spreading it out along the surface of the plate 220. Upon deaeration, a stationary pick-up tube 240 removes the deaerated liquid, which collects on the outer edge of the plate 220. The Cornell Versator generates high shear due to the high differential speed between the plate 220 and the stationary pickup tube 240.
Vacuum deaerators are process is utilized in the manufacture of various products in numerous industries, for example, the chemical, food cosmetics, and pharmaceutical industries. As product demands increase in these industries, the need arises for improvements in vacuum deaerators and components thereof.